On the Cost of Caching Locator/ID Mappings

Very recent activities in the IETF and in the Routing Research Group (RRG) of the IRTG focus on defining a new Internet ar- chitecture, in order to solve scalability issues related to interdo- main routing. The approach that is being explored is based on the separation of the end-systems’ addressing space (the identi- fiers) and the routing locators’ space. This separation is meant to alleviate the routing burden of the Default Free Zone, but it implies the need of distributing and storing mappings between identifiers and locators on caches placed on routers. In this pa- per we evaluate the cost of maintaining these caches when the distribution mechanism is based on a pull model. Taking as a reference the LISP protocol, we base our evaluation on real Net- flow traces collected on the border router of our campus network. We thoroughly analyze the impact of the locator/ID separation, and related cost, showing that there is a trade-off between the dynamism of the mapping distribution protocol, the demand in terms of bandwidth, and the size of the caches